All animal creatures have to sleep. By being awake we all, from the smallest one to the biggest ones spend energy. And while we sleep we get rest and recover. What's interesting here is that smaller creature apparently need a lot longer hours of sleep than larger animals. For example, elephants sleep only 4 hours a day, whales – from 1 to 2, and giraffes even less than that! At the same time opossums and cats sleep two thirds of the day, or even more!
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Infographic by: sleepopolis.com